Base station device, gateway device, call connecting method, and wireless communication system

ABSTRACT

A system is provided which is capable of connecting a call without degrading the security level in a mobile terminal network, even when a call addressed to a user equipment (UE) arrives via the Internet or a home network. A femto base station receives a packet addressed to a UE via the Internet or a home network, and starts a paging procedure. The UE establishes an RRC connection to the femto base station. The UE transmits, to the femto base station, a paging response addressed to the SGSN. The femto base station performs NAS verification. If the femto base station detects the paging response to a paging request that the femto base station itself has issued, the femto base station changes the service type of the service request received from the UE from the paging response to signaling.

BACKGROUND Technical Field

The present invention relates to a base station apparatus, gatewayapparatus, call connection establishment method and wirelesscommunication system, for controlling call connection establishment.

Description of the Related Art

A macro cell base station apparatus for wireless communication (macrobase station) having a large cell radius is provided mainly outdoors,and, in addition to this, 3rd Generation Partnership Project (3GPP) isstudying to provide a femto cell base station apparatus (femto basestation) having a cell radius of approximately several tens of meters ina household, office, and an indoor facility such as a restaurant.

FIG. 1 shows a system configuration in the event a femto base station isprovided in a household. As shown in FIG. 1, in a household, it islikely that, in addition to a femto base station, an IP telephone, anIP-TV, and furthermore a plurality of personal computers and suchlikedevices, share one xDSL, FTTH or suchlike Internet-connecting networkvia fixed-line system. The femto base station is connected with a corenetwork via a concentrator (GW).

Lately, to provide a solution for increasing traffic of, for example,data communication, many mobile operators are forced to improveequipment and facilities. Consequently, by introducing a femto basestation, it is possible to keep the cost lower than providing additionalbase stations outdoors and off-load indoor-originated communicationtraffic directly to the Internet. By this means, it is expected toreduce load of a core network in a mobile network system. Also, infuture, a communication device in a user's premise and a mobile terminalare expected to be able to communicate directly with each other, via afemto base station, without traversing mobile operator's core network,and provide various interactive services to the user.

Next, the steps of call connection establishment in an IMT-2000 packetsystem, disclosed in non-patent literature 1 for example, will bedescribed using FIG. 2. Referring to FIG. 2, a UE, after a connectionestablished with a Radio Network Controller (RNC) through Radio ResourceControl (RRC) call connection establishment procedure (ST 11), requestsa start of service to an SGSN, using a service request, which is a GPRSMobility Management (GMM) protocol signal (ST 12). A service requestmessage includes information to request a signaling connection(connection for signaling) between the UE and the SGSN (service type:signaling).

The SGSN performs authentication processing for the UE having requestedsignaling connection (ST 13), and, if, as a result of this, the UE isidentified as a valid UE, indicates RNC to initiate ciphering processingfor a radio connection by a security mode command, which is an RANAPsignal (ST 14). Then, if ciphering processing has been performedsuccessfully, the UE requests call connection establishment using a PDPcontext activation request (or “Activate Packet Data Protocol ContextRequest”), which is a Session Management (SM) signal (ST 15).

In this SM signal, an Access Point Name (APN) to specify a target datanetwork (packet data network: PDN) for the connection is provided, sothat the SGSN, upon receiving this SM signal, acquires IP addressinformation of the GGSN to connect to, based on the APN information,through a Domain Name System (DNS) procedure. Then, upon successfullyacquiring the IP address of the GGSN, the SGSN transmits an RABAssignment Request, which is an RANAP signal, to the RNC, and requeststunnel establishment between the RNC and the SGSN (ST 16).

Next, the SGSN, having checked the tunnel established between the RNCand the SGSN, transmits a PDP context creating request (or “Create PDPContext Request”), which is a GPRS Tunneling Protocol (GTP) signal, tothe GGSN having the IP address acquired through the DNS procedure, andrequests call connection establishment for the UE (ST 17).

In this GTP signal, also, APN information is provided, so that GGSNhaving received the GTP signal can identify the PDN to establish theconnection, based on the APN information. When the GGSN successfullycompletes call connection establishment processing, the SGSN is reportedthat call connection establishment processing has been performedsuccessfully, by means of a PDP context creating response (or “CreatePDP Context Response”), which is a GTP signal (ST 18). At this point intime the GGSN configures routing information (i.e., route selection) forthe UE, and manages the routing information as PDP context.

Next, a response signal from the GGSN is transmitted to the UE using aPDP context activation accept (or “Activate PDP Context Accept”), whichis an SM signal (ST 19), and the UE starts transmitting and receivinguser data (i.e., packet communication) (ST 20). At this point in time,the SGSN configures routing information for the UE, and manages therouting information as PDP context.

In this way, through the above series of processing, an IMT-2000 packetsystem sets up logical connections between a UE and a GGSN on a perconnection basis and performs tunneling, thereby enabling packetcommunication.

Next, the steps of traffic off-loading for communication traffic betweena femto base station and the Internet or home network, withouttraversing mobile operator's core network, will be described using FIG.3. Note that, parts in FIG. 3 that are the same as in FIG. 2 will beassigned the same reference codes as in FIG. 2, and their detaileddescriptions will be omitted. Assume here that the femto base stationhas the SGSN and GGSN functionalities shown in FIG. 2. Also, since theUE cannot be attached to more than one SGSN at the same time, anotherassumption is given that the UE keeps being attached to one SGSN that islocated in a core network.

The femto base station, having received a PDP context activation requesttransmitted from the UE, does not transfer this request to the SGSN,and, instead, selects a PDN to connect to, based on APN information,using its own SGSN function (ST 21). Assume that, for example, the ISPto provide broadband access to the user's home can be identified basedon information included in APN.

The femto base station determines to process call connectionestablishment for the UE using its co-located GGSN function which thefemto base station owns. Later, by performing processing from ST 16 toST 20 in FIG. 2 using the GGSN, SGSN, RNC and Node B functionalitiesprovided in the femto base station, it is possible to establish logicalconnections between the UE and the GGSN, on a per connection basis, andconsequently enable communication traffic originating from a femto basestation to be off-loaded directly to the Internet or home network,without traversing a mobile operator's core network.

CITATION LIST Non-Patent Literature

NPL 1: 3GPP TS23.060 v7.8.0

BRIEF SUMMARY Technical Problem

However, there are, for example, following problems on the above-notedoff-loading method to incoming traffic via a femto base station directlyfrom the Internet or home network.

Normally, the steps of receiving an incoming call for a UE in idle stateare initiated as a paging procedure with broadcasting within a specificarea to discover the UE. With the paging, when information to indicatean incoming call for a UE arrives at an SGSN, the SGSN transmitsinformation indicating that a UE has received the incoming call, to basestations in the UE's registered service area.

The UE can detect whether there is an incoming call for the UE based onsignals from a base station at predetermined timing. When there is anincoming call detected, the UE transmits a service request shown in FIG.2 to the SGSN (ST 12). The service request includes information toindicate that the service request is a response to paging (service type:paging response). Following this, through the call connectionestablishment procedure shown in FIG. 2, logical connections areestablished between the UE and the GGSN on a per connection basis andtunneling is performed, thereby enabling packet communication.

Next, FIG. 4 shows the steps of call connection establishment when anincoming call for a UE arrives at a femto base station from the Internetor home network. In FIG. 4, a femto base station receives a packet for aUE from the Internet or home network (ST 22).

The femto base station transmits a paging message to the UE using theco-located SGSN and GGSN functionalities in the femto base station (ST23).

As mentioned above, the UE is attached to an SGSN in a core network,and, upon detecting paging, transmits a service request includinginformation as a paging response, to the SGSN in the core network (ST24).

In the SGSN in the core network having received the service request(service type: paging response) from the UE, there is no record pagingmessage having been transmitted to the UE, so that the SGSN detects thatan incorrect service request has been received from the UE, andtransmits a service rejecting message (or “Service Reject”) to the UE(ST 25).

If a service request is rejected by the SGSN, subsequent securityprocedures (UE authentication, preparation related to radio intervalciphering, etc.) cannot be performed, and the UE is unable tosuccessfully finish the call connection establishment procedure for theincoming call from the Internet or home network.

A possible solution to the above problem is to temporarily attach the UEto an SGSN co-located in a femto base station, and process a servicerequest from the UE in the co-located SGSN in the femto base station.However, in this case, since security procedures are carried out in theco-located SGSN of the femto base station, information related to the UEauthentication needs to be moved from the core network SGSN to the femtocell. That is to say, important information related to userauthentication is memorized in a femto base station which is likely tobe provided in a general user's home, and, as a result of this, there isa possibility that the security level might be degraded.

It is therefore one of objectives of the present invention to provide abase station apparatus, gateway apparatus, call connection establishmentmethod and wireless communication system that, when there is an incomingcall for a UE from the Internet or home network, are able to carry outconnection setup successfully without decreasing the security level in amobile communication network.

Solution to Problem

A base station apparatus according to the present invention adopts aconfiguration having: a receiving section that receives a pagingresponse to a paging from a wireless communication terminal apparatus; ajudging section that judges whether the paging response is a response tothe paging which the base station apparatus has issued;

and a transmitting section that, when the paging response is judged tobe a response to the paging which the base station apparatus has issued,includes a request for change of a service request in the pagingresponse, and transmits the paging response to a gateway apparatus.

Advantageous Effects of Invention

According to the present invention, when there is an incoming call for aUE from the Internet or home network, it is possible to carry out callconnection establishment successfully without degrading the securitylevel in a mobile communication network.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 shows a configuration of a wireless communication system;

FIG. 2 is a sequence diagram showing the steps of call connectionestablishment in an IMT-2000 packet system;

FIG. 3 is a sequence diagram showing the steps of directly off-loadingcommunication traffic originating from a femto base station, to theInternet or home network;

FIG. 4 is a sequence diagram showing the steps of call connectionestablishment in the event there is an incoming call for a UE, in afemto base station, from the Internet or home network;

FIG. 5 shows a configuration of a wireless communication systemaccording to embodiment 1 of the present invention;

FIG. 6 is a block diagram showing a configuration of the femto basestation shown in FIG. 5;

FIG. 7 is a block diagram showing a configuration of the GW shown inFIG. 5;

FIG. 8 is a sequence diagram showing the steps of call connectionestablishment between a UE and a femto base station according toembodiment 1 of the present invention;

FIG. 9A shows direct transfer contents of an HNBAP or RUA signal;

FIG. 9B shows information elements of NAS updating request information;

FIG. 10A shows direct transfer contents of an S1AP signal by which NASinformation is first transmitted from a UE to a core network;

FIG. 10B shows information elements of a NAS updating command;

FIG. 11 is a block diagram showing a configuration of a femto basestation according to embodiment 2 of the present invention;

FIG. 12 is a sequence diagram showing the steps of call connectionestablishment between a UE and a femto base station according toembodiment 2 of the present invention;

FIG. 13 is a block diagram showing a configuration of a femto basestation according to embodiment 3 of the present invention;

FIG. 14 is a block diagram showing a configuration of a UE according toembodiment 3 of the present invention; and

FIG. 15 is a sequence diagram showing the steps of call connectionestablishment between a UE and a femto base station according toembodiment 3 of the present invention.

DETAILED DESCRIPTION

Now, embodiments of the present invention will be described in detailwith reference to the accompanying drawings. The following embodimentswill be each described based on a wireless access technologystandardized by 3GPP, such as General Packet Radio Service (GPRS) andUniversal Mobile Telecommunications System (UMTS).

However the present invention is not limited to Long Term Evolution(LTE) that is being presently standardized by 3GPP or wireless accesstechnologies standardized by 3GPP, but is equally applicable to WLAN(Wireless Local Area Network), Worldwide Interoperability for MicrowaveAccess (WiMAX) technologies such as IEEE802.16, IEEE802.16e andIEEE802.16m, and still other wireless access technologies such as 3GPP2.

Embodiment 1

FIG. 5 shows a configuration of a wireless communication systemaccording to embodiment 1 of the present invention. The wirelesscommunication system shown in FIG. 5 has UE 100, femto base station 110,GW 140, and a core network.

Femto base station 110 is provided in a user's premise (home) 131,assigns and manages resources for wireless connections, receivesinformation that is transferred via the physical layer of UE 100 foruplink traffic, and transfers received downlink data for UE 100. That isto say, femto base station 110 plays a role of an access point for UE100, on a wireless access network.

UE 100 communicates with the core network, the Internet or home network,via femto base station 110. In the home network, PC 130 is provided forexample, and PC 130 and UE 100 communicate directly, via femto basestation 110, without traversing the core network, and provides variousinteractive services to the user.

GW 140 is located between femto base station 110 and a core network, andconcentrates and relays communications between SGSN 150 in the corenetwork and a plurality of femto base stations 110. Such a configurationto place femto base station non-transparently to the core network nodesmakes it possible to deploy a large number of femto base stations 110,without increasing the processing load of core network equipments.

SGSN 150 and GGSN 160 are provided in the core network, so that SGSN150, upon receiving a service request from UE 100, performs anauthentication process for UE 100 and controls call connectionestablishment processing between GW 140 and GGSN 160. Also, GGSN 160manages addresses for data communication, to assign to UE 100, requiredfor packet communication.

FIG. 6 is a block diagram showing a configuration of femto base station110 shown in FIG. 5. In FIG. 6, receiving section 111 outputs an RRCsignal and uplink user data transmitted from UE 100, to wireless controlsection 112. Also, receiving section 111 outputs a Home Node BApplication Part (HNBAP) signal, RANAP User Adaptation (RUA) signal anddownlink user data for UE 100, transmitted from GW 140, to GW controlsection 113. Also, receiving section 111 outputs data received as inputdirectly from the Internet or home network, to core network functionsection 114.

Wireless control section 112 terminates the RRC signal output fromreceiving section 111, and establishes an RRC connection with UE 100.Also, from the RRC signal, wireless control section 112 judges that UE100 is requesting transmission/reception of Non-Access Stratum (NAS)information with the core network, and outputs NAS information to GWcontrol section 113. Furthermore, wireless control section 112 encodescontrol information output from GW control section 113 as an RRC signal,and outputs the RRC signal to UE 100 via transmitting section 115.

Also, wireless control section 112, upon receiving uplink user data fromUE 100, terminates the wireless protocol and outputs the user data to GWcontrol section 113. Also, wireless control section 112, upon receivingdownlink user data for UE 100 from GW control section 113, performswireless protocol processing according to predetermined parameter 1 andtransmits data to UE 100 via transmitting section 115.

GW control section 113 processes the HNBAP or RUA signal output fromreceiving section 111, and terminates the RANAP signal from the corenetwork. Also, GW control section 113 judges whether or not it isnecessary to transmit an RRC signal to UE 100, based on the RANAP signalor a control signal output from network function section 114, and, iftransmission is necessary, outputs control information that is outputfrom the core network or core network function section 114, to wirelesscontrol section 112.

Also, GW control section 113 requests core network function section 114to judge whether or not NAS information for UE 100 output from wirelesscontrol section 112, or NAS information from the core network, needs tobe processed. Based on the judgment result in core network functionsection 114, GW control section 113 includes NAS information for UE 100in RANAP, adds NAS updating request information to an HNBAP or RUAsignal, and transmits these to GW 140 via transmitting section 115.

Also, when NAS information for UE 100 is output from core networkfunction section 114, GW control section 113 outputs the NAS informationto wireless control section 112. GW control section 113, upon receivingdownlink user data for UE 100 from GW 140 or core network functionsection 114, terminates transport network protocol and outputs user datato wireless control section 112. Also, when uplink user data for UE 100is output from wireless control section 112, GW control section 113performs transport network protocol processing according topredetermined parameter 1, and transmits uplink user data to GW 140 viatransmitting section 115, or outputs uplink user data to core networkfunction section 114.

Core network function section 114 receives data for UE 100, receiveddirectly from the Internet or home network via receiving section 111,and outputs a control signal for establishing logical connection for UE100, to GW control section 113.

Also, core network function section 114 determines whether femto basestation 110 needs to process the NAS information received from UE 100based on NAS information processing necessity judging request outputfrom GW control section 113. Upon processing NAS information, corenetwork function section 114 outputs information for requesting GW 140to update this NAS information based on NAS information received, orgenerates NAS information for UE 100 and outputs the generated NASinformation to GW control section 113. On the other hand, when NASinformation needs not be processed, core network function section 114instructs GW control section 113 to promptly output the received NASinformation to GW 140. Incidentally, core network function section 114functions as a judging means.

Also, when uplink user data for UE 100 is output from GW control section113, core network function section 114 performs packet data networkprotocol processing according to predetermined parameter 1, andtransmits data to the Internet or home network via transmitting section115. Also, when downlink user data for UE 100 is output from receivingsection 111, core network function section 114 terminates the packetdata network protocol and outputs data to GW control section 113.

Core network function section 114 has non-CN incoming call detectionsection 116, and, when there is an incoming call directly from theInternet or user's home network without involving the core network (CN),non-CN incoming call detection section 116 memorizes that the incomingcall is a call from outside the core network.

Transmitting section 115 transmits an RRC control signal output fromwireless control section 112, to UE 100. Also, transmitting section 115transmits downlink data for UE 100, output from wireless control section112, to UE 100. Also, transmitting section 115 transmits NAS informationfor UE 100, output from GW control section 113, to GW 140. Also,transmitting section 115 transmits uplink user data for UE 100, outputfrom GW control section 113, to GW 140, and outputs uplink user data forUE 100, output from core network function section 114, to the Internetor home network.

FIG. 7 is a block diagram showing a configuration of GW 140 shown inFIG. 5. In FIG. 7, receiving section 141 outputs an HNBAP or RUA signalcontaining NAS information for UE 100, transmitted from femto basestation 110, and an RANAP signal, transmitted from the core network, tofemto control section 142. Also, receiving section 141, upon receivinguplink user data for UE 100 from femto base station 110, performspredetermined transport network protocol processing, and transmits theuplink user data to the core network via transmitting section 144. Also,upon receiving downlink user data for UE 100 from the core network,receiving section 141 performs predetermined transport network protocolprocessing with the user data, and transmits the downlink user data tofemto base station 110 via transmitting section 144.

Femto control section 142 includes the RANAP signal output fromreceiving section 141 in an HNBAP or RUA signal according topredetermined parameter 1, and transmits this to femto base station 110via transmitting section 144. Also, when an HNBAP or RUA signalincluding NAS information for UE 100 is output from receiving section141, femto control section 142 terminates the HNBAP or RUA signal, picksup the RANAP signal including NAS information for UE 100, and outputsthis RANAP signal to core network control section 143 with the NASupdating request information in the HNBAP or RUA signal.

Core network control section 143 has NAS information updating section145, and, when RANAP signal containing NAS information for UE 100 isoutput from femto control section 142, NAS information updating section145 overwrites and updates the NAS information for UE 100 contained inthe RANAP signal, based on the NAS updating request information in HNBAPor RUA signal reported likewise. Also, core network control section 143outputs the RANAP signal containing updated NAS information for UE 100,to the core network, via transmitting section 144.

Transmitting section 144 transmits the HNBAP or RUA signal containingNAS information for UE 100, output from femto control section 142, tofemto base station 110. Also, transmitting section 144 transmits theRANAP signal output from core network control section 143 and containingupdated NAS information for UE 100, to the core network. Also,transmitting section 144 transmits the uplink user data for UE 100output from receiving section 141, to the core network, and transmitsthe downlink user data to femto base station 110.

Next, the steps of call connection establishment between UE 100 andfemto base station 110 when there is an incoming call from the Internetor home premise network for UE 100 in femto base station 110, will bedescribed using FIG. 8.

In FIG. 8, in ST 101, femto base station 110 receives a packet for UE100 from the Internet or home network. Core network function section 144in femto base station 110, having received a packet for UE 100, startsthe steps for establishing logical connection for UE 100. In ST 102,core network function section 114 starts a paging step to indicate thata call for UE 100 has been received. Then, femto base station 110memorizes, in non-CN incoming call detection section 116, informationindicating that a paging procedure has been initiated due to a call forUE 100 having been received from the Internet or home network.

In ST 103, UE 100 detects that a call for UE 100 has been received, froma paging request, and establishes RRC connection with femto base station110. In ST 104, UE 100 transmits a service request towards currentlyconnecting SGSN 150, via femto base station 110, in order to answer thepaging request. Incidentally, the service request includes informationindicating a paging response.

In ST 105, femto base station 110 decides whether to process the NASsignal received from UE 100 or to forward it to the core network. Corenetwork function section 114 of femto base station 110, upon receiving aNAS information processing necessity judging request from GW controlsection 113, judges whether the received NAS information (servicerequest: paging response) is a response to the paging request whichfemto base station 110 transmitted in ST 102, based on informationmemorized in non-CN incoming call detection section 116 (NAS check).

In ST 106, femto base station 110 encodes the NAS information (servicerequest: paging response) received from UE 100 using an RANAP directtransfer, encodes RANAP using a direct transfer of a protocol complyingwith the control interface specifications between femto base station 110and GW 140, and outputs the results to GW 140.

FIG. 9A shows the direct transfer contents of an HNBAP or RUA signal.Also, FIG. 9B shows information elements of NAS updating requestinformation (or “SR Modification Request”). In FIG. 9A, a message typeindicating that the message is a direct transfer, a CN domain IDindicating to which CS/CP domain the message is directed, and an RANAPmessage, which is upper protocol RANAP itself, are included.Furthermore, a direct transfer contains an SR Modification Request, and,as shown in FIG. 9B, this SR Modification Request contains informationindicating the necessity to modify the type of the service request inthe RANAP message (“Modification Necessity”), and informationrepresenting the actual contents to be modified when modification isrequired (“Modification Contents”).

If, according to the judgment result in ST 105, NAS information (servicerequest: paging response) that has been received is a response to apaging request which femto base station 110 has issued, the HNBAP or RUAsignal contains NAS updating request information. In this case, the IEtype of modification necessity in FIG. 9B shows “Necessary,” and the IEtype of modification contents shows change from paging response tosignaling (paging response ->signaling). If, on the other hand, thispaging response is a regular paging response to a paging request fromthe core network, the HNBAP or RUA signal does not contain NAS updatingrequest information, the IE type of modification necessity shows “NotNecessary” and the IE type of modification contents is not referenced inGW 140.

In ST 107, GW 140, having received the HNBAP or RUA signal from femtobase station 110, terminates HNBAP or RUA, and picks up the RANAPsignal. Then, if NAS updating request information is included in theHNBAP or RUA signal, that is, if the IE type of modification necessityin FIG. 9B shows “Necessary” and the IE type of modification contentsshows change from paging response to signaling, GW 140 terminates theRANAP, picks up NAS information (service request: paging response) forUE 100, and updates service type in the NAS information from pagingresponse to signaling. Also, if NAS updating request information is notincluded in the HNBAP or RUA signal, that is, if the IE type ofmodification necessity in FIG. 9B shows “Not Necessary,” GW 140 does notprocess the RANAP signal picked up, and thereafter carries out callconnection establishment steps prescribed by 3GPP, with the corenetwork.

In ST 108, GW 140 encodes the updated NAS information (service request:signaling) by an RANAP direct transfer again, and transmits the resultto SGSN 150 in the core network.

In ST 109, SGSN 150, having received NAS information (service request:signaling) from UE 100, judges that a regular service initiation requesthas been received from UE 100, and carries out call connectionestablishment steps prescribed by 3GPP, with UE 100, via femto basestation 110.

In ST 110, the core network having finished security procedures with UE100, transmits “service accept,” which indicates that predeterminedsteps in response to a service request from UE 100 have beensuccessfully performed, to UE 100. Then, if, according to the result ofjudging the necessity to process NAS information received from SGSN 150,received NAS information indicates a service accept, core networkfunction section 114 of femto base station 110 detects that securityprocedures have been successfully carried out between UE 100 and SGSN150, and the signaling connection has been successfully establishedbetween them.

In ST 111, using predetermined parameter 1, femto base station 110requests UE 100 to start the steps of establishing connection forservice with UE 100 (or “Request PDP Context Activation”). APN, which isinformation to specify the connection destination data network (PDN), isset as one of the predetermined parameter 1, and this APN alsorepresents, for example, the ISP network providing broadband access tothe user's home.

In ST 112, using the parameter acquired in ST 111, UE 100 requests callconnection establishment to femto base station 110 by a PDP contextactivation request (or “Activate PDP Context Request”), which is an SM(Session Management) signal.

In ST 113, a radio bearer (DTCH) that is adequate for service isestablished between femto base station 110 and UE 100.

In ST 114, femto base station 110, having checked that a radio bearerwith UE 100 has been successfully established, transmits a PDP contextactivation accept (or “Activate PDP Context Accept”), which is an SMsignal, to UE 100, and, in ST 115, UE 100 and femto base station 110start transmitting and receiving user data (packet communication).

Thus, according to embodiment 1, when there is an incoming call for a UEin a femto base station from the Internet or home network, only whendetecting that the paging response received from the UE is the responseto the request from the femto base station, the femto base stationmodifies the service type of a service request transmitted from the UEfrom paging response to signaling, and forwards the paging responsemessage to a core network. When security procedures are successfullyfinished between the UE and the core network, the femto base stationcarries out call connection establishment steps directly between thefemto base station and the UE, so that it is possible to transmitcommunication traffic having directly arrived at the femto base stationfrom the Internet or home network, without degrading the security levelin a mobile communication network, and without traversing the corenetwork.

Also, although embodiment 1 has been described using UMTS system as anexample such that a GW updates NAS information, in an LTE/SAE (Long TermEvolution/System Architecture Evolution) system, the contents of directtransfer message shown in FIG. 9 are different.

FIG. 10A shows the contents of a direct transfer that transfers NASinformation, which is contained in an S1AP signal representing a controlprotocol between a femto base station and a core network, and which istransmitted first from a UE, to a core network, in an LTE/SAE system.Also, FIG. 10B shows information elements of a NAS updating command (or“SR Modification Indicator”). In FIG. 10A, a message type, which showsan indication of a direct transfer to forward NAS informationtransmitted first from a UE, to a core network, a NAS-PDU, which is NASinformation itself, an information element for specifying a UE, a femtobase station and so on (eNB UE S1AP ID, TAI, E-UTRAN CGI, etc.), and areason to start RRC connection (RRC establishment cause), are included.Furthermore, in the direct transfer to transfer the NAS information thatis transmitted first from the UE, an SR Modification Indicator isincluded, and, as shown in FIG. 10B, this SR Modification Requestincludes information to show the necessity to modify the type of aservice request in the NAS-PDU (“Modification Necessity”), andinformation to show the actual contents of modulation in the eventmodification is necessary (“Modification Contents”).

In the core network having received the SR Modification Indicator, ifthe IE type of modification necessity in FIG. 10B shows “Necessary” andthe IE type of modification contents shows change from paging responseto signaling, NAS information having a service type of a paging responseis updated to NAS information having a service type of signaling, andsubsequent processing is continued.

Embodiment 2

Embodiment 1 has been described such that a femto base stationdetermines whether or not it is necessary to update a service requestfrom a UE, and a GW actually updates the service type of a servicerequest from the UE from paging response to signaling. Consequently, incase that signaling is concentrated in a GW on a temporary basis, the GWis likely to suffer increased load due to RANAP signal terminatingprocessing and NAS information updating processing to be performed. Asolution to avoid such possibility will be described in this embodiment2 of the present invention.

FIG. 11 is a block diagram showing a configuration of femto base station120 according to embodiment 2 of the present invention. Note that, partsin FIG. 11 that are the same as in FIG. 6 will be assigned the samereference codes as in FIG. 6, and their detailed descriptions will beomitted. FIG. 11 is different from FIG. 6 in adding NAS informationupdating section 145 to core network function section 124.

When NAS information for UE 100 and NAS updating request information areoutput from GW control section 113, NAS information updating section 145updates the NAS information for UE 100 based on the NAS updating requestinformation.

FIG. 12 is a sequence diagram showing the steps of call connectionestablishment between UR 100 and femto base station 120 according toembodiment 2 of the present invention. Note that, parts in FIG. 12 thatare the same as in FIG. 8 will be assigned the same reference codes asin FIG. 8, and their detailed descriptions will be omitted.

In FIG. 12, in ST 206, femto base station 120 picks up NAS informationfor UE 100 (service request: paging response), and updates service typein the NAS information from paging response to signaling.

In ST 207, femto base station 120 encodes the updated NAS information(service request: signaling) using an RANAP direct transfer, encodesthis RANAP signal using a direct transfer of a protocol complying withthe control interface specifications between femto base station 120 andGW 140 (for example, HNBAP or RUA), and outputs the results to GW 140.

In this way, with embodiment 2, a femto base station itself updates NASinformation from a UE, and by this means is able to reduce theprocessing load of a GW and transmit communication traffic that directlyarrives at the femto base station from the Internet or home network, tothe UE, without a core network.

Embodiment 3

Embodiment 1 and embodiment 2 have been described such that a GW orfemto base station updates the service type of a UE service request frompaging response to signaling. However, in LTE/SAE system, which isdirected to an object of providing improved mobile communication serviceand which is a next-generation mobile communication system havingevolved from UMTS, it is required to ensure integrity andconfidentiality to NAS information between a UE and a CN. It wouldbecome possible risk which degrades the security level to allow anintermediate node such as a GW and/or femto base station to modifydirectly the NAS information. So, a femto base station and UE that areapplicable to both UMTS and LTE/SAE system will be described in thisembodiment 3 of the present invention.

FIG. 13 is a block diagram showing a configuration of femto base station125 according to embodiment 3 of the present invention. Note that, partsin FIG. 13 that are the same as in FIG. 6 will be assigned the samereference codes as in FIG. 6, and their detailed descriptions will heomitted. FIG. 13 is different from FIG. 6 in adding paging processingsection 127 to core network function section 126.

When non-CN incoming call detection information for UE 100 is outputfrom non-CN incoming call detection section 116, paging processingsection 127 creates a paging request including a non-CN incoming callinformation, and transmits this paging request to UE 100, viatransmitting section 115.

FIG. 14 is a block diagram showing a configuration of UE 100 accordingto embodiment 3 of the present invention. In FIG. 14, receiving section101 outputs an RRC signal and downlink user data transmitted from femtobase station 125, to wireless control section 102.

Wireless control section 102 terminates the RRC signal output fromreceiving section 101, and establishes an RRC connection with femto basestation 125. Also, wireless control section 102 monitors a pagingchannel (PCH) transmitted from femto base station 125 at predeterminedtiming, and judges whether or not a paging request for UE 100 isincluded. Wireless control section 102 further has non-CN incoming calldetection section 103, and, when a paging request for UE 100 isreceived, non-CN incoming call detection section 103 judges whether ornot non-CN incoming call information is included. If non-CN incomingcall information is included, non-CN incoming call detection section 103includes non-CN incoming call information in a paging request andoutputs this paging request to NAS control section 104. Also, wirelesscontrol section 102 encodes NAS information output from NAS controlsection 104 as an RRC signal, and outputs the RRC signal to femto basestation 125, via transmitting section 106, using uplink transmissionsteps prescribed by 3GPP.

NAS control section 104, upon receiving a paging request includingnon-CN incoming call information from non-CN incoming call detectionsection 103, creates a service request having a service type ofsignaling, and outputs the created service request (NAS information) towireless control section 102. If the paging request does not containnon-CN incoming call information, NAS control section 104 outputs aservice request having a service type of a paging response, to wirelesscontrol section 102 in a regular manner.

Transmitting section 106 transmits an RRC signal containing NASinformation, output from wireless control section 102, to femto basestation 125. Also, transmitting section 106 transmits user data outputfrom higher application (not shown in the figure), to femto base station125.

FIG. 15 is a sequence diagram showing the steps of call connectionestablishment between UE 100 and femto base station 125, according toembodiment 3 of the present invention. Note that, parts in FIG. 15 thatare the same as in FIG. 12 will be assigned the same reference codes asin FIG. 12, and their detailed descriptions will be omitted.

In FIG. 15, in ST 302, paging processing section 127 of femto basestation 125 includes non-CN incoming call information in a pagingrequest for UE 100, and transmits this paging request to UE 100.

In ST 303, NAS control section 104 of UE 100 creates a service requesthaving a service type of signaling (NAS information creation).

In ST 304, UE 100 transmits an RRC signal containing NAS information andhaving a service type of signaling, created in ST 303, to femto basestation 125.

In this way, according to embodiment 3, a femto base station includesnon-CN incoming call information in a paging request and transmits thispaging request, and, upon receiving processing of the paging requestincluding non-CN incoming call information, a UE itself modifies NASinformation, so that it is possible to guarantee the impartiality andciphering of NAS information, and, consequently, in both UMTS andLTE/SAE systems, it is possible to transmit communication traffic thatdirectly arrives at the femto base station from the Internet or homenetwork, to the UE, without traversing mobile operator's core network.

Embodiments of the present invention have been described above.

Also, although eases have been described with the above embodiment asexamples where the present invention is configured by hardware, thepresent invention can also be realized by software.

Each function block employed in the description of each of theaforementioned embodiments may typically be implemented as an LSIconstituted by an integrated circuit. These may be individual chips orpartially or totally contained on a single chip. “LSI” is adopted herebut this may also be referred to as “IC,” “system LSI,” “super LSI,” or“ultra LSI” depending on differing extents of integration.

Further, the method of circuit integration is not limited to LSI's, andimplementation using dedicated circuitry or general purpose processorsis also possible. After LSI manufacture, utilization of a programmableFPGA (Field Programmable Gate

Array) or a reconfigurable processor where connections and settings ofcircuit cells within an LSI can be reconfigured is also possible.

Further, if integrated circuit technology comes out to replace LSI's asa result of the advancement of semiconductor technology or a derivativeother technology, it is naturally also possible to carry out functionblock integration using this technology. Application of biotechnology isalso possible.

The disclosure of Japanese Patent Application No. 2008-280339, filed onOct. 30, 2008, including the specification, drawings and abstract, isincorporated herein by reference in its entirety.

INDUSTRIAL APPLICABILITY

The base station apparatus, gateway apparatus, call connectionestablishment method and wireless communication system according to thepresent invention are applicable to, for example, mobile communicationsystems.

1. An integrated circuit configured to control operation of a userequipment (UE), the integrated circuit comprising: reception circuitry,which, in operation, receives a paging message from a traffic offloadingapparatus for the UE when the UE is in idle mode, the paging messageregarding downlink offload traffic arriving at the traffic offloadingapparatus; control circuitry, which is coupled to the receptioncircuitry and which, in operation, controls transmission of a servicerequest message as a paging response to the traffic offloadingapparatus, a service type in the service request message indicating thepaging response which triggers the traffic offloading apparatus tomodify the service type in the service request message to indicate aUE-initiated service request and to send the modified service requestmessage to a first Serving General Packet Service Support Node (SGSN).2. The integrated circuit according to claim 1, wherein the trafficoffloading apparatus is a femto base station.
 3. The integrated circuitaccording to claim 1, wherein the traffic offloading apparatus has aGateway General Support Node (GGSN) functionality.
 4. The integratedcircuit according to claim 1, wherein the traffic offloading apparatusis a second SGSN different from the first SGSN.